1. Negotiating Unsolicited Connections to a Service Listening Behind a Firewall Ben Stroud CS525 Spring 10

2.  So What is the Problem Anyway?  How Port Prediction Works  Implementation Issues  Success Rates  Not Covering ◦ Alternative Solutions ◦ Security Concerns  Questions 4/23/2010 Stroud 2

3.  Firewalls will generally not allow unsolicited connections from the outside world into the “protected zone”.  To participate in peer to peer networks users have to open ports.  How to keep users from having to manually configure routers? 4/23/2010 Stroud 3

4. 4/23/2010 Stroud 4 Live Online Streaming of Television Via a Distributed Network

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6.  For Large Networks Negotiation Server Must be very Robust ◦ Overlapped I/O with large pool of sockets  UDT ◦ TCP has additional considerations ◦ Implementation this is based on used UDP ◦ We still needed TCP delivery guarantees ◦ TCP + UDP = UDT 4/23/2010 Stroud 6

7.  Able to bypass 95% of consumer level routers  Failures due to port prediction or bad connections?  Unable to predict random offsets  Won’t work on the Most Restrictive Networks ◦ Confined to HTTP for inbound traffic 4/23/2010 Stroud 7

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9. 4/23/2010 Stroud 9  See Full Report